Bacteria resistant to hydro-alcoholic hand wash gels

A bacterial species responsible for infections in the hospital has developed a tolerance to hydro-alcoholic solutions widely used in the hospital for twenty years.

A species of bacteria responsible for infections in the hospital would have developed a tolerance … to hydro-alcoholic solutions (SHA), gels supposed to precisely annihilate the unwanted bacteria. If antibiotic resistance is already a global public health issue as the World Health Organization frequently reminds us this news is particularly worrying.

Because SHAs are the most effective way to prevent bacteria from being passed from hand to hand. They were introduced in the early 2000s in hospitals, not only because they facilitate the observance of hand washing (faster and less restrictive gesture), but also because their action quickly proved more effective than a soap wash. Since 2001, the Technical Committee on Nosocomial Infections has been recommending

and the updated 2009 recommendations even advocate the removal of antiseptic soap for the hands of caregivers because it is not effective enough and poorly tolerated.

Bacteria more resistant to alcohol

But the possibility that bacteria become resistant to SHA was almost never considered. And for good reason, the alcohol they contain is supposed to kill bacteria much faster than soap by dissolving their outer membrane. The effectiveness of the soap is based on a mechanical action, removing the layer of fat on the epidermis with the bacteria found there. But Australian researchers at the University of Melbourne have observed the disturbing evolution of Enterococcus faecium over the last twenty years.

Their study published on the bioRxiv biology preproduction server shows that this bacterial species responsible for nosocomial infections has become more resistant to alcohol. For this, the team led by Professor Tim Stinear analyzed 139 samples taken between 1997 and 2015 in hospitals. By testing these bacteria in mice, it shows that the most recent bacteria were ten times more tolerant to alcohol than colonies from older lines. Experiments that indicate that the genome of the bacteria has probably adapted, making their membrane more resistant to alcohol.

“This is a very serious and credible threat,” says Philippe Glaser, head of the Institute for Ecology and Evolution of Antibiotic Resistance at the Pasteur Institute. The researcher, who did not participate in the study, said he had “selected the summary of Tim Stinear for oral communication at the conference on bacterial resistance that we organize in March at the Pasteur Institute.” The authors note in their work that while infections caused by methicillin-resistant staphylococci fell sharply, those caused by bacteria of the genus Enterococcus increased fivefold over this period.

Escape from disinfection

For Philippe Glaser, “we must see that this bacterial species, Enterococcus faecium, is already resistant enough to stress, which explains its adaptation to the hospital and its ability to cause nosocomial infections. It is normally sensitive to these treatments, but some mutations can reduce this susceptibility and thus allow an escape to disinfection. This work shows that such strains are selected at the hospital and can spread. “

The study also suggests that SHA could be better used to prevent these adaptive phenomena. It is sufficient to use a gel containing a little less alcohol than another to give more chances to some of these bacteria to survive and thus facilitate the development of tolerance. “It was probably naïve to think that” superbugs “would not be able to adapt to alcohol-based disinfectants, Judge Matthew O’Sullivan, of Sydney University. When you consider all that we introduced to try to fight the bacteria, we see that they always find a way to evolve to circumvent “, he explained.